Hydraulic-pneumatic power assist apparatus



Aug. 4, 1964 H. s. HOARD, JR

HYDRAULIC-PNEUMATIC POWER ASSIST APPARATUS Filed July 3, 1961 INVENTOR.

HOMER .s. Ha/mw, .rx.

Fla. 2. (PR/0.? ART) 5% lie.

United States Patent M 3,143,338 HYDRAULIC-PNEUMATIC POWER ASSISTAPPARATUS Homer S. Hoard, 513, San Jose, Calif assignor, by mesneassignments, to Philco Corporation, Philadelphia, Pa.,

a corporation of Deiaware Filed .lnly 3, 1961, Ser. No. 121,773 6Claims. (G. 267-1) This invention relates to hydraulic-pneumatic powerassist apparatus, and more particularly to counter-balancing meansembodying a hydraulic-pneumatic linkage system.

Mechanical linkage systems adapted to move relatively large objectsnormally are provided with counterbalance means comprising a large massof material, such for example as metal or concrete, so arranged as toprovide the desired balancing forces for the linkage system. A largemass of this type often represents a large static load which also mustbe supported by the base structure of the linkage system. Additionalstatic loading due to the counterbalancing mass requires of course thatthe base structure be reinforced, which requirement involves increasedmaterials, costs, and the like.

It is therefore a broad objective of this invention to provide a simpleand effective counterbalancing means for a mechanical linkage systemeliminating the need for a counterbalancing mass.

It is a specific object of the invention to provide novelcounterbalancing force producing apparatus.

It is a more specific objective of the invention to provide ahydro-pneumatic system in combination with a four-bar linkage in placeof a counterbalancing mass.

In achievement of the foregoing and other objectives the inventioncontemplates provision of counterbalancing means for a mechanicallinkage system for driving a large unbalanced mass, comprising, in apreferred embodiment: cylinder means having a piston working therein,said piston including piston rod means projecting from one end of thecylinder, one of said means being attached to movable structureincluding a relatively large mass and the other of said means beingattached to stationary structure, said cylinder having a single port inthe region of one end and a pair of ports in the region of the otherend, each said port accommodating movement of fluid to and from thecylinder as the piston moves therein; fluid supply means associated withsaid single port; a pair of fluid conduit means associated with saidpair of cylinder ports; accumulator means disposed in fluid flowcommunication with each of said conduit means of said pair; pressurecompensated flow control valve means disposed in one of said conduitmeans; and normally closed pressure relief valve means disposed in theother of said conduit means and operative to open in response to anincrease of pres sure in said cylinder and said one conduit means.

It is a feature of the invention that the piston is disposed and adaptedto close the port communicating with said conduit means in which thepressure compensated flow control valve means is disposed, as it movestoward the other port.

By virtue of the foregoing novel combination of flow control valve meansand pressure relief valve means with the accumulator and cylinder thereis achieved both a counterbalancing and snubbing action for the largemass and its related mechanical linkage system.

The foregoing as well as other objects and advantages will best beunderstood from a consideration of the following description, taken inlight of the accompanying drawing in which:

FIGURE 1 is an elevational view of parabolic antenna apparatus embodyingcounterbalancing means made in accordance with the invention;

3,143,338 Patented Aug. 4, 1964 FIGURE 2 is a view similar to FIGURE 1,but illustrating counterbalancing means heretofore known in the art; and

FIGURE 3 is a somewhat diagrammatic showing of hydraulic-pneumaticcounterbalancing means embodying the invention, a portion of which meansis seen also in FIGURE 1.

With more particular reference to the drawing, and first to FIGURE 1,the'invention is depicted for exemplary purposes as being embodied in arelatively large parabolic antenna structure of a type currently used inthe tracking of guided missiles, earth satellites, and the like. It Willbe understood, however, that counterbalancing means embodying theinvention also has utility in combination with crane, elevator, or otherlarge machine structures requiring balanced linkage systems.

The aforementioned antenna structure comprises a tower or base 10erected upon the ground G and including rotatable carriage 19 and gimbalmeans 11 that pivotally and rotatably mount a parabolic antenna 12.While it is to be understood that gimbal means 11 and carriage 19provide 3-dimensional movement of antenna 12, the present detaileddescription will be made with respect only to Z-dimensional movement ofthe antenna, since principles of the invention can readily be understoodby way of such simplified showing.

Making reference also to the diagrammatic showing of FIGURE 3, it isseen that carriage 19 for the antenna comprising the mass to be balancedand which is shown for convenience at 12 as a concentrated mass,comprises journal means 13 for antenna mounting shaft 14. Gimbal means11 includes antenna support 18 carried, intermediate end portionsthereof by shaft 14. A motor 34 (FIG- URE 3) is disposed and adapted todrive shaft 14, rotatably to position the latter and antenna 12 throughmovements of gimbal means 11 at elevations in accordance with thedirectional arrows applied thereto. It will be understod that azimuthalpositioning of the antenna is achieved by rotating, through suitabledrive means, carriage 19 about a vertical axis and with respect to base10.

In particular accordance with the invention, counterbalancing means 15comprises cylinder means 16 having a piston 17 working therein. Piston17 includes a piston rod 21 projecting from one end of cylinder means 16and pivotally attached at 22 to antenna support 18, and the end 23 ofcylinder means 16 is pivotally attached at 24 to carriage 19. Theconstruction and arrangement of the counterbalancing means 15 as thusfar described is such that pivotal attachments 22 and 24 of rod 21 andcylinder means 16, respectively, interconnect carriage 19 with antennasupporting gimbal means 11. It will also be noted that carriage 19,support 18, piston 17 with rod 21, and cylinder means 16 comprise theequivalent of a four bar linkage. Cylinder means 16 includes, in theregion of its end 23, a single opening or port 28 connected by aflexible conduit 25 to means defining a supply of low pressure fluiddesignated generally by the numeral 26. It is the purpose of the fluidsupply means 26 to maintain the presence of fluid in the lower portionof cylinder 16 and sealing ring 20 precludes leakage of fluid acrosspiston 17.

The other end of cylinder means 16 includes a pair of openings or ports27 and 31 connected to flexible conduits 32 and 33, respectively. Itwill be further noted that piston 17 includes a cylindrical projection17a at its rod end. This projection 17a is receivable within restrictedportion 16a of cylinder means 16, through which portion port 27 extends.Note that port 31 extends through a wall of cylinder means 16 just aheadof port 27 and restricted portion 16a, as respects upward movement ofpiston 16. The construction and arrangement of the piston 17, cylindermeans 16, and ports 27, 31

is such that as the piston moves upwardly from the broken-line showingthereof, in the direction of the solid directional arrow, the projection17a will first enter por- .tion 16a to close port 27, leaving port 31open. Continued upward movement of piston 17 causes its main bodyportion then to halt just short of closing port 31, as illustrated "inthe full-line showing of the piston. As will be understood from whatfollows, this closing of port 27 activates means which provides asnubbing action for the antenna, which action is characterized by a lowantenna deceleration value as it moves to a limit of its travel.

Conduit 32 is disposed in fluid flow communication with a pressurecompensated fluid flow control valve 35 having an inlet port 36-and anoutlet port 37. The valve additionally comprises a valve plunger orspool 41 having a variable fluid flow regulating portion 42 movabletransversely of valve bore or conduit 43. One end of plunger 41comprises a piston 40 that slides within a relativelysmall cylinder 44ported through line 45 to valve conduit 43 at a region downstream withrespect to plunger flow regulating portion 42. The other end of plunger41 comprises a relatively large spring-loaded piston 46 that slideswithin a cylinder 47 that is ported, through a line 51, to valve conduit43 at a region downstream of the porting of line 45 thereto. Arestrictor having a preselected flow rate is disposed at 43aintermediate the connection of lines 45 and 51 to conduit 43. The outletport 37 of valve 35 is connected to a hydraulic-pneumatic accumulator 52of known construction by means ofa conduit53.

Conduit 33 leads to and is disposed in fluid flow communication with apressure relief valve 54, comprising a cylinder 55 having an inlet port56 in one end thereof and an outlet port 57 in a side wall portionthereof. A piston 61 is slidable within cylinder 55 and is springloadednormally to maintain outlet port 57 closed, as shown, which port 57 isconnected to accumulator 52 by conduits 62 and 53. A check valve 63 isdisposed in a conduit 64 interconnecting conduits 33 and 53 as shown.

In the operation of the above described apparatus, in which connectionmovements first to be described are indicated by unbroken arrows, andconsidering that motor 34 has been energized to move antenna 12 in aclockwise direction upon rotatable shaft 14, piston 17 moves towardopenings 27 and 31 and fluid is caused to flow through conduit 32, valve35, and conduit 53 into accumulator 52. As fluid moves into theaccumulator gas contained therein, nitrogen for example, is compressedand stores energy in accordance with the degree of compression. Thisstored energy is utilizable later, to exert a counterbalancing forcewhen the antenna is moved in the opposite direction as will behereinafter described. Fluid does not flow at this stage through conduit33 due to the fact that both check valve 63 and relief valve 54 areclosed. Any tendencies to increased speed, due for example to effects ofwind or variations in the speed of drive motor 34, are compensated forby the differential action of fluid pressure forces on pistons 46 and 41which regulate the position of fluid flow regulating plunger portion 42.

Valve 35, according to known practice, maintains its fluid flow settingregardless of the changing load on the fluid. The metering orifice orrestrictor 43a is preselected for the required fluid flow rate, andcompensator spool 41 operates to maintain a fixed pressure across themetering restrictor 43a'for a wide range of pressure loading.

The increased force required of piston 17 due to the increase in anglewith the vertical to counter the moment of force exerted by thevertically directed center of gravity of the antenna 12, as its centerof gravity moves closer to the horizontal, is compensated for, orcounterbalanced, by the increased compression of gaseous fluid withinaccumulator 52. As the illustrated full clockwise positioning of antenna12 is reached, at which time piston 17 has moved upwardly from thebroken line showing,

the small portion 17a of piston 17 is caused to enter restricted portion16a of cylinder 16 and thereby seals port 27 from the larger diametercylinder. This closure immediately creates a pressure increase incylinder 16, forcing fluid through port 31 and conduit 33 (wavy arrows),into cylinder 55 of relief valve 54, against the reactive force of itscompression spring 540. The increased pressure achieves the desireddecelerative snubbing force for the antenna as it moves to the end ofits downward travel. As spring 54a is compressed further, piston 61moves to uncover port 57 to permit fluid flow therethrough (wavy arrow)and again to subject the piston 17 to the pressure built up within theaccumulator 52.

. Upon energizing motor 34 to elevate antenna 12, by moving the same ina counter-clockwise direction, piston 17 moves in the opposite direction(dotted arrow) whereupon the pressure is relieved within relief valve 54and it again is closed (dotted arrow), unrestricted flow of fluid fromthe accumulator 52 to cylinder 16 taking place through check valve 63,until such time port 27 is opened by the unseating of piston portion 17afrom cylinder portion 16a. Unrestricted return fluid flow (dottedarrows) then continues, such flow being effected by expansion of the gaswithin the accumulator 52, through check valve 63 and conduit 33, somereturn flow taking place through valve 35 and conduit 32. Concurrentwith the flow of fluid into the upper end of cylinder 16 there is a flowof fluid from its lower end through opening 28 and fluid conduit 25 tolow pressure fluid supply reservoir 26. It is this expansion of the gasin the accumulator that furnishes the counterbalancing force for thelinkage system, which force is transmitted by the fluid to piston 17.

In contrast with the above disclosed invention, typical prior artcounterbalance means for antenna 12a, as shown in FIGURE 2, comprises asteel-encased lead weight 15a mounted upon antenna support 18a thelatter being pivotally mounted at 14a upon carriage 1911. This weight15a of course constitutes an undesirable static load upon towerstructure 19a and also presents an undesirable wind resistancesurface,which disadvantageous loading is overcome by the present invention.Furthermore, there is required in this apparatus a separate snubbingmeans operative independently of the counterbalancing lead weight 1511.

From the foregoing description it will be appreciated that the inventionachieves, in a unitary hydro-pneumatic system not only a uniformcounterbflancing action, but also a snubbing or damping action which inthe disclosed apparatus advantageously prevents undue stressing of theantenna as would occur if the latter struck the tower structure due toexcessive velocity and consequent excursion of antenna movement.

I claim:

1. In combination, a massive structure, support means for saidstructure, means defining a pivot for mounting said structure upon saidsupport means with its center of gravity to one side of said supportmeans and providing for pivotal movements of its center of gravitywithin predetermined upper and lower fixed limits to said one side ofsaid support means, motor means for effecting such pivotal movements, afluid cylinder, a piston movable within said cylinder and including rodmeans extending from an end thereof, said cylinder and piston comprisinglinkagemeans extending between and pivotally connected to said supportmeans and to a portion of said massive structure disposed to the side ofsaid pivot for mounting said structure opposite its center of gravity,said piston and cylinder thereby being pivotal as a unit relative tosaid support means and to said massive structure as it is moved aboutits pivot, accumulator means for storing fluid under pressure, andconduit means connected to said accumulator means and said cylindertoward the end thereof from which said rod means extends, fluid underpressure within said accumulator means thereby being ef fective to exertforces upon said piston for statically counterbalancing said massivestructure as its center of gravity is moved about its pivot.

2. The combination according to claim 1, and characterized in that saidcylinder is pivotally connected to said support means and said rod meansis pivotally connected to said massive structure.

3. The combination according to claim 1, and characterized in that saidfluid is a liquid and said accumulator means is of thehydraulic-pneumatic type.

4. In combination, a massive structure, support means for saidstructure, means defining a pivot for mounting said structure upon saidsupport means with its center of gravity to one side of said supportmeans and providing for movement of its center of gravity to said oneside of said support means within predetermined upper and lower fixedlimits, motor means for eflecting such pivotal movements, hydrauliccylinder and piston means pivotally interconnecting said support meansand a region of said massive structure disposed to the side of saidpivot for mounting the latter opposite its center of gravity, first andsecond conduits connected to said cylinder, said first conduit beingdisposed and adapted for closure by said piston means as it is caused tomove toward the connection of said conduits to said cylinder uponpivotal movements of said massive structure to its lower limit by saidmotor means, hydraulic-pneumatic accumulator means connected to saidconduits and providing fluid forces for statically counterbalancing saidmassive structure as its center of gravity is moved about its pivot,fluid flow control valve means disposed in said first conduit andrestricting flow of fluid between said accumulator means and saidcylinder as said massive structure is moved toward its lower limit,check valve means operative to by-pass said control valve means andpermit unrestricted fluid flow between said accumulator means and saidcylinder when said massive structure is pivoted toward its upper limit,and a fluid pressure relief valve disposed in said second conduitadapted to accommodate sudden excessive increases in fluid pressure insaid cylinder, said massive structure being counterbalanced in any ofits positions by forces imparted thereto by compressed fluid in saidcylinder reacting against said piston throughout such pivotal movements.

5. In combination, a massive structure, support means for saidstructure, means defining a pivot for mounting said structure upon saidsupport means with its center of gravity to one side of said supportmeans and providing for pivotal movement of its center of gravity withinpredetermined fixed limits to said one side of said support means, motormeans for eflecting such pivotal movemerits, a hydraulic cylinder, meanspivotally linking said cylinder to said support means, a piston movablewithin said hydraulic cylinder and including rod means extending from anend thereof, means pivotally linking said rod means to a region of saidmassive structure disposed to the side of said pivot for mounting saidstructure opposite its center of gravity, said piston and cylinderthereby being pivotable as a unit relative to said support means andsaid massive structure as it is moved about its pivot, conduit meansconnected to said cylinder toward the end thereof from which said rodmeans extends, and hydraulic-pneumatic accumulator means connected tosaid conduit means and operative to exert hydraulic forces upon saidpiston thereby statically counterbalancing said massive structure as itscenter of gravity is moved about its pivot.

6. In combination, a massive structure, support means for saidstructure, means defining a pivot for mounting said structure upon saidsupport means with its center of gravity to one side of said supportmeans and providing for pivotal movements of its center of gravitywithin predetermined upper and lower fixed limits to said one side ofsaid support means, motor means for eflecting such pivotal movements, afluid cylinder, a piston movable within said cylinder and including rodmeans extending from an end thereof, said cylinder and piston comprisinglinkage means extending between and pivotally connected to said supportmeans and to a portion of said massive structure spaced from said pivotfor mounting said structure, said piston and cylinder thereby beingpivotal as a unit relative to said support means and to said massivestructure as it is moved about its pivot, accumulator means for storingfluid under pressure, and conduit means connected to said accumulatormeans and said cylinder toward the end thereof from which said rod meansextends, fluid under pressure within said accumulator means therebybeing effective to exert forces upon said piston for staticallycounterbalancing said massive structure as its center of gravity ismoved about its pivot.

References Cited in the file of this patent UNITED STATES PATENTS840,877 Steedman Jan. 8, 1907 1,821,787 Black Sept. 1, 1931 1,829,643Cannon Oct. 20, 1931 2,001,988 Temple May 21, 1935 2,704,996 Peterson etal Mar. 29, 1955 2,719,510 Elder Oct. 4, 1955 2,783,742 Shafer Mar. 5,1957

5. IN COMBINATION, A MASSIVE STRUCTURE, SUPPORT MEANS FOR SAIDSTRUCTURE, MEANS DEFINING A PIVOT FOR MOUNTING SAID STRUCTURE UPON SAIDSUPPORT MEANS WITH ITS CENTER OF GRAVITY TO ONE SIDE OF SAID SUPPORTMEANS AND PROVIDING FOR PIVOTAL MOVEMENT OF ITS CENTER OF GRAVITY WITHINPREDETERMINED FIXED LIMITS TO SAID ONE SIDE OF SAID SUPPORT MEANS, MOTORMEANS FOR EFFECTING SUCH PIVOTAL MOVEMENTS, A HYDRAULIC CYLINDER, MEANSPIVOTALLY LINKING SAID CYLINDER TO SAID SUPPORT MEANS, A PISTON MOVABLEWITHIN SAID HYDRAULIC CYLINDER AND INCLUDING ROD MEANS EXTENDING FROM ANEND THEREOF, MEANS PIVOTALLY LINKING SAID ROD MEANS TO A REGION OF SAIDMASSIVE STRUCTURE DISPOSED TO THE SIDE OF SAID PIVOT FOR MOUNTING SAIDSTRUCTURE OPPOSITE ITS CENTER OF GRAVITY, SAID PISTON AND CYLINDERTHEREBY BEING PIVOTABLE AS A UNIT RELATIVE TO SAID SUPPORT MEANS ANDSAID MASSIVE STRUCTURE AS IT IS MOVED ABOUT ITS PIVOT, CONDUIT MEANSCONNECTED TO SAID CYLINDER TOWARD THE END